DCS系统在热电厂锅炉控制中的运用

本文通过分析热电厂锅炉运行过程中的控制方案,研究了热电厂锅炉控制系统的组成,探讨了DCS系统在热电厂锅炉应用中遇到的常见故障以及解决方案,对于热电厂机组的稳定运行具有一定的参考价值。     

DCS在锅炉自动控制系统的应用

DCS系统作为自动化控制系统的重要应用,被广泛应用。在锅炉的自动化控制系统中,DCS的应用越来越多。介绍了DCS锅炉系统控制的硬件配置,功能,阐述了锅炉燃烧控制系统,流量控制系统,以及安全保护等方面的应用。为研究DCS系统在锅炉自动化控制提供一定的借鉴。     

自动控制技术在宣钢160t/h锅炉中的应用

介绍了宣钢160t/h中温中压燃气式锅炉的工艺和自动控制系统的构成及控制方式,锅炉本体采用了ABB公司的DCS控制系统完成了宣钢160t/h锅炉给水系统、燃烧系统、风烟系统等各子系统的控制功能,并重点阐述了中温中压燃气式锅炉给水自动控制的设计和实现。     

火电厂300MW机组直接空冷系统的控制与运行

在分析了火电厂直接空冷系统的工艺过程和功能特点的基础上,介绍了基于DCS控制的300MW机组直接空冷控制系统的组成、测点布置及控制功能,并对系统的启动准备、启动运行、正常运行、低负荷运行、关闭运行、非正常运行、紧急运行等工况进行了详细分析,实际运行结果表明直接空冷冬季防冻措施灵活可靠,直接空冷可通过改变风机转速或停运风机或使风机反转来调节空冷凝汽器的进风量或直至吸热风来防止空冷凝汽器冻结,调节相对灵活,效果良好。     

工业锅炉分布式控制系统设计

针对某工业燃煤锅炉的工艺流程和控制要求,设计了一套基于现场总线技术的锅炉分布式计算机控制系统.给出了控制系统的总体结构,设计了锅炉燃烧系统和公共水系统的下位机控制程序,开发了上位监控软件和监控画面,并通过Profibus总线实现了现场控制站和变频器间的数据通信.现场运行结果表明,所设计的锅炉分布式控制系统运行稳定可靠,取得了较好的控制效果.     

比例调节在锅炉燃烧控制中的探讨

本文描述了利用比例调节的控制方式有效经济的实现锅炉的燃烧控制,实现了主要工艺的自动控制、画面监控、报警、趋势记录等一系列功能,实践证明本系统在锅炉燃料、送风、负压控制方面是可行的,具有调节燃烧稳定、高效等特点,系统运行稳定可靠,故障点查找方便,便于调度管理,节能降耗显著,带来了可观的经济效益和社会效益。     

发电厂氧化镁湿法脱硫的自动控制

介绍了太钢自备电厂7#、8#锅炉氧化镁法脱硫工艺自动控制系统的硬件配置、控制方式及功能特点,该系统的稳定可靠运行,为烟气脱硫的高效达标排放发挥了重要作用。     

DCS下的锅炉电气自动控制系统的应用分析

锅炉的自动化控制的水平和可靠性直接关系到锅炉运行和产品质量,锅炉DCS自动控制系统不仅可以节能减排,还可以提高锅炉运行的安全性,改善工人工作环境以及提高劳动生产率。本文分析燃气锅炉系统控制任务的基础上,还探讨了工业自动控制系统的设计运行,具有显著的经济效益和社会效益。     

DCS系统在锅炉发电系统中的应用

从和利时MACSV—DCS自动控制系统在25T锅炉发电中的应用,介绍该套锅炉中DCS的网络结构和软硬件的组成,并对其在本锅炉发电系统中应用的不足进行了分析。     

基于PLC的火电厂烟气脱硫控制系统研究与设计

根据烟气脱硫系统的工艺特点,提出了系统的自动控制要求和控制方式.采用可编程控制器(PLC)作下位机、工业控制计算机(PC)作上位机与参数测量传感器、变送器、操作控制器等组成集散型控制系统(DCS),详细设计了电源电路、数据采集电路以及通信电路等功能模块.PLC负责完成数据采集与自动控制,PC机与PLC相互通信,监视脱硫系统的运行,保证了脱硫系统的安全、经济与稳定运行.     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.     

A rigorous proof of MIMO channel capacity’s increase with antenna number

It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output（MIMO） communication systems. In this letter, a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas. The proof is based on the famous capacity formula of Foschini and Gans with matrix theory.